The present invention relates to a cushion block assembly for a cylinder which supports a bowling ball backstop for an automatic pinsetting or pinspotting machine for bowling alleys. Cushion block assemblies presently used for such purposes do not permit rapid installation and removal to the cylinder which supports the bowling ball backstop. One of the blocks must be removed to install or remove the bowling ball backstop. The presently used cushion block assemblies permit upward movement of the cylinder. When the shock absorber attached to the bowling ball backstop is worn, the upward movement may be sufficient to permit the bowling ball to become wedged under the bowling ball backstop.